Apparatus for forming lamp filaments



g- 1956 O. MANN EIAL 2,759,498

APPARATUS FOR FORMING LAMP F'ILAMENTS Original Filed May 28, 1949 4Sheets-Sheet l TIC/24 1 .1: 5:: iii ii! 55!.

/ H ii h'i L. n l l m' ul m m m Oliver Mann i9 4 Ralph z gggas ATTOE/VEY1956 o. MANN EIAL 2,759,498

APPARATUS FOR FORMING LAMP FILAMENTS Original Filed May 28, 1949 4Sheets-Sheet 2 I, I f l 1? g; H n H 3 w 6 O/[Ver Mann IN V EN T0115ATTORNEY Aug. 21, 1956 O. MANN ETAL 2,759,498

I APPARATUS FOR FORMING LAMP FILAMENTS Original Filed May 28, 1949 4Sheets-Sheet 3 2? f I I [L T F hill 1 I I II .1

.I I; MIMI; I I

O// 1 2? Man/7 9 Ralph 5. 7720mczs IN VEN T 0R5 ATTORNEY Aug. 21, 1956o. MANN ETAL 2,759,498

APPARATUS FOR FORMING LAMP FILAMEINTS Original Filed May 28, 1949 4Sheets-Shet 4 O/frer Mann Ra/pf) 5. 7720/7/05 INVENTORS ATTORNEY UnitedStates Patent E R FQRMING'LANIP F E N Oliver Mann, Danvers, and 'RalphlB. ThomasySalem, -Mass., asslgnors to Sylvania'ElectrieProducts Inc.,Salem,'. Mass., acorporation of -Massachusetts )iyided and this 360,496

3 (Qlq140-r71-5) This invention relates to electric lamp filaments andmoreparticularly to filaments of the typeemployed in high-wattagelamps'such as projection lamps, for example.

In the manufacture of'filarnents for-projectionlamps, especiallyfilaments of thebi-plane -type, considerable care must be exercised toinsure uniform length of the several segments of: the-filament,uniformspacing between each segment and uniform spacing between theplanes of the segments. Since a projection lamp filament of high qualityrequires very close tolerances, considerable care must be taken duringthe fabricating process to insure the attainment of these tolerances.

vWe have found that some--ofthe methods previously employed in thefabrication of -bi-plane -projection lamp filaments have left muchto-be'desired. One of these methods comprises forming-the filament fromspaced coiling with the length -,of: the wire ineachfilament-supportingloop being a function of the length of the spacing between each coilsegment and the shape of the loop being determined by the peripheralpoints at which the spaced portion. starts'and ends. In this and othermethods,'it has been the practice to transfer the filament, after it hasbeen formed to a firing jig so that when heated toa temperature.sufiicient to effect a setting thereof it willhave apre-determined form.When the filament.is.=formed from spaced coiling or from continuouscoilingiand transferred to afiringjig, the close tolerances and uniformspacing described above. are quite diflicult to attain with any degreeof manufacturing consistency.

Accordingly therefore, an object of our inventionis to provide .anapparatus for fabricating a bi-plane-projection lamp filament which ischaracterized by uniformity in the length oftheseveral segmentsthereof,.uniformity in the spacing between the segments, and uniformityin the spacing between the planes, all within very-close tolerances.

Another object is to provideanapparatus for fabricating a bi-planeprojection lamp filament which is characterized by uniformity in thespacing between the loops thereof, accurate alignment of -eachwith-reference,to each other in both,thehorizontal-and theyert-icalplane, anduniformity; in shape.

In accordance with the principles of our invention, segmented coils areformed andjiggedfrom continuous coiling by bendingandpartiallymnwindingthe;continuous i ng to f h s ve e me ts o thprojection lamp filament and the severalloops ,therebetween from whichthe filament is supported. This operation isperformed on a mandrel.which'may serve-as the firingjig as well as the forming fixture.

F r h bj s, a va ge :an features .will be apparent: from the followingdescription thereof .when read in-; conjuncti on with he, aCQOmPQQY Ilgr w ng ih Fi ur 1 i .P R t Y --Y of-th -apparatus ofour inv ntion-:Figurel, i aside elewational-= iew Q fii Length-detache coiled tungstenwire: whiehis' foldedtand iiggedmnztheitpparatus of :Figure 1.

'--Figure 3 isa-side-elevationalview of the mandrel on which thecoiled-coiled wireofg'FigurejZ is folded.

Figure 4 is a-side elevational view of-the .mandr'el of Figure- 3 withthe coiled coiled-wire;folded thereon.

Figure '5 is asideelevational view of the rear end of the jig of Figure1.

'Figure6 is a'top view--of the rear end"of-' the 'jig of Figure 1.

' Figure 7-is a top-view, partly insection, of "thefront end of thejig-of Figure- 1.

Figure 8 isa side-elevational view of the front end of the jig of Figure1.

'Figure'9' is'afrontview-of the-frontend of the jig of Figure 1.

Figure 10a, 5, c, c', .d,-e, f-andff'isa-plura1ity of fragmentarydetailsillustrating the manner inwhich the coiled coiled tungsten-wire ofFigure l is folded on the mandrel of fFigure' 3.

- Referring to Figure 1, the apparatus of our invention comprises a jig,generally designated by the numeral I, mounted inablock 2, which--is, inturn, mounted on a support 3 upstan'ding from a. base member 4. The jig1 comprises va casing 5 with-achamber 6 extending longitudinally therein"from one --end thereof and isprovided with-a covenplate7. -A' fixe'dslide 8' anda-movable slide 9 are seated within the ehamben 6--a=ndamandrel 10 is disposed therebetween. A -locking .screw '11 extendsthroughaside -of the casing 5,f=into the: chamber" 6, and engagesthefixed slide 8. By-tightening this screw, an operator is abletoloclethe: slides 8 and-9 and the mandrel': 10 tonne: another andithecasing 5. The outer ends ofithe slides 8 and9are:provideduwith;laterally extending projections; hereinafterreferred:toiasrguideshelvesz 12 and 13 respectively. 'IThe-movable: slide9.-is:pr-ovided' with a screwz'l4 -extending-j laterally therefrom, .toservewas a handle by which an operator: may; rnove: the: slideoutwardly, the-purpose ofi-whioh; is rdescnibed'more-fully below, and asa stop for limiting the inward movement thereof.

'rT-he manner inttwhichwthe jig 1 .is. 'mounte.d in. block 2, and'thelblock'i is mounted. onisupportfii is illustrated: in Figures:1'-,-Smandz6. :The jig?Lis-rotatably'mounted in block 2 by means of; ashafta15wwhichiprojectsafroman end. of the 1 jig and throughwan-aperture therefor: in the block, and a ringz16 locked tattle-shaftrl5rwby' set-screw 17.- The adjacent engaging-facesof the ringsl6'andzthe block'2..are provided 'withmeanszfor, indicating to anoperatorwhenathejig has'beenrotated 1 ;:degrees, the purpose! of-whichwill be described :more fully: below. ,This meansncomprisesra pair of.dimples;18; in the ring 16 and aspring-biased -ba1l19 in thetbloeklAtspring 20,-seated in an :aperture 'thereforjin the:bloek.2,,;is-placed under iflnSibIltbyzza set-screw 12.1, hereyaexerting a! force which tends to efiectia-seat'ing; of the -ba1l:19,in adimplelS.

The block 2 is secured to. the snpport :31by means of a locking screw:22 which extends through the: support 3 into a threaded zapertureithereforrin ,theblock 2. This arrangement; permits ,the' angleofqelevlation of; the jig 1 to beadjusted iso :that 'it maytbelocated-indie most satisfact ry working p s ion; forahy; given op rFigures '7, x8, .and 9. show in. detail. the slides ,8 and 9 andthemandrel 10 ,therebetween; and the manner in which these members areseated intthechamber 6y provided herefor in the GaSiHg: .The mandrel,1.-0wisa plate of high-refractory. materialsuch :asmolybdenum forexample, and is providedwitha-plurality" of lateral slots 23on-bothfaces-adjacentone end thereof, and a, plurality ofindexinggrooves; Mon 3; face adjacent-the. other end thereof (Fig. 3).

'As Sh OWIJ.5il] -Figure .-7, ,theslides 8 and -9, 2 which areelongatedi-metalpmembers,-are provideda on -their adjacent, engagingraces with c perating r-l ngi n z r which define aachembertor-athe-.mandrel 10. ,These grooves are deeper at the exposed ends of theslides to provide space for the several segments of the filamentary coilwhen it is folded on the mandrel (Figures 7 and 9). The fixed slide 8 ispivotally mounted on a pin which prevents longitudinal movement thereofin the chamber 6. As shown in Figure 7, the fixed slide 8 is providedwith a resilient spring member 26, one end of which is fixed to theslide and the other end of which is engageable with the indexing grooves24 on the mandrel 10, the purpose of which is described below. Theoutside ends of the slides 8 and 9 adjacent the guide shelves 12 and 13respectively are cut away as at 27 to provide space for the filamentarycoil during each folding cycle and to insure proper insertion of aforming tool between the turns of the coil.

The method of forming, from continuous coiling, segmented coils havinguniform loops between adjacent segments, on the above-describedapparatus, is illustrated in the several views which comprise Figure 10,when read in conjunction with the other figures, particularly Figures 1,7, 8 and 9. The jig 1 is oriented by positioning it so that the lockingscrew 11 is on the left side thereof from an operators point of view.The screw 11 is loosened, and the mandrel-10 is inserted in the chambertherefor defined by the longitudinal grooves in the engaging faces ofthe slides 8 and 9 with the indexing grooves on the side adjacent thefixed slide. The mandrel is properly seated when it comes to restagainst the resilient spring member 26 attached to the fixed slide 8.

The elongated coil of wire 28 is positioned in the jig 1 by inserting anend thereof in the innermost slot 23 on the left side of the mandrel 10,with the free portion thereof extending upwardly from the top of theslot (Fig. 10a) When the segment 29 of the coil 28 has thus been seated,the screw 11 is tightened to lock the mandrel 10 within the slides 8 and9 and the slides to the casing 5. Folding of the wire 28 about themandrel 10 by bending and partially unwinding it is accomplished by anoperator with the aid of a pair of forming tools 30 and 31, each ofwhich is preferably provided with a beveled tip 32 and 33 respectively.

Forming tool 30, with the bevelled side 32 up, is positioned flat on thesurface of the guide shelf 12 and is moved in the direction of the slotin the opposite side of the mandrel and into engagement with the coil 28(Figure 1011) until it is more than half way past the longitudinalcenter thereof between the two adjacent turns of the coil at the planeof the upper edge of the mandrel. With forming tool 30 thus seated,forming tool 31 is moved into position flat on the surface of thebevelled edge 32 of the tool 30 and in engagement with the coil 28 (Fig.101)). Tool 31 is then raised and rolled forward slightly until the coil28 is disposed substantially perpendicular to the segment 29 thereof'(Fig. 10c) and is extending in the direction of the slot in theopposite face of the mandrel (Fig. 10c). Both tools are then withdrawnfrom engagement with the coil 28.

With the first forming tool 30 held vertically, and the bevelled side 32to the right, the operator brings it into engagement with the coil 28 sothat one turn thereof, turn 35, is disposed on the left side of the tool(Fig. 10d). Turn 35, after the folding operation has been completed,defines a loop by means of which the filament may be supported in alamp. With the first forming tool 30 thus positioned, the second formingtool 31 is brought into engagement with the bevelled edge 32 of tool 30(Figure lOe). A rotary forward movement is imparted to the tool 31,thereby effecting a further bending and partial unwinding of the coil 28and causing it to move downwardly into a slot 23 on the right side ofthe mandrel 10 (Figure 10 p Tools 30 and 31 are then removed fromengagement with the coil 28. Segment 36 has now been formed and isdisposed as shown in Fig. 10g. The locking screw 11 (Figures 1 and 7) isnow loosened, and the movable slide 9 is drawn forwardly a distancesufiicient to enclose segment 36 of the coil 28 which has just beenpositioned in a groove 23 on the right side of the mandrel 10 (Figs. 10fand f), with the lip of the slide 9 covering and holding segment 36 inposition on the mandrel. The screw 11 is then tightened.

The jig 1 is then rotated clockwise degrees to properly position theseveral parts thereof for the next operation. When this is done, theunfolded portion of the coil 28 is then disposed in the same relativeposition as that in which the coil 28 is shown in Figure 10a,except'that the movable slide 9 instead of the fixed slide 8 will now bedisposed on the left. The sequence of steps described above andillustrated in the several parts of Figure 10 is then repeated. Uponcompletion thereof, the screw 11 is loosened, and the mandrel 10 andslide 9 are pushed inwardly together one indexing position on theindexing grooves 24 (Fig. 7).

The operation of folding the coil 28 by bending and partially unwindingit on the mandrel 18 to form a plurality of segments is continued withthe folding steps performed as described above and illustrated in theseveral parts of Figure 10 and the jig rotated 180 degrees after eachsegment has been positioned in its proper slot 23. The relative positionof the mandrel 10 and the movable slide 9 is adjusted after eachfoldingcycle by alternately drawing the slide 9 forward and pushing themandrel 10 and slide 9 inward, as described above. The slide 9 is drawnforward when it is on the operators right, and the mandrel 10 and slide9 are pushed in when the slide 9 is on the operators left.

After the folding of the coil 28 on the mandrel 10 has been completed,the mandrel 10, with the coil 28 folded thereon, is withdrawn from thejig 1 and may be positioned on a suitable fixture and fired to effect asetting of the coil.

Although the apparatus of our invention has been specifically describedand illustrated with reference to the fabrication of bi-plane electriclamp filaments, its adaptability to the fabrication of other segmentedelectric lamp filaments will be readily appreciated by those skilled inthe art. For example, segmented mono'plane filaments may be readilyfabricated by folding all of the filament segments on one side of themandrel.

This application is a division of our co-pending application SerialNumber 95,986, filed May 28, 1949.

What we claim is:

1. Apparatus for forming, from a continuously wound coil of filamentwire, an electric lamp filament, having a plurality of coiled segmentswith a filament supporting loop between each segment, said apparatuscomprising: a jig having a chamber therein; a pair of slides disposed inthe chamber in said jig with a portion thereof lying outside saidchamber; a mandrel slidably seated in said jig between said slides, saidmandrel having a plurality of apertures therein for receiving the coiledsegments and, in cooperation with said pair of slides within which saidmandrel is disposed, to enclose and hold the coiled segments as they areformed; and a guide shelf on the outside end of each said slides.

2. Apparatus for forming, from a continuously wound coil of filamentwire, an electric lamp filament, having a plurality of coiled segmentswith a filament-supporting loop between each segment, said apparatuscomprising: a support member; a jig rotatably mounted on said supportmember, said jig having a chamber therein; a fixed slide and a movableslide disposed in the chamber in said jig with a portion of each lyingoutside said chamber; a mandrel slidably seated in said jig between saidslides, said mandrel having a plurality of apertures therein forreceiving the coiled segments and, in cooperation with said pair ofslides within which said mandrel is disposed, to enclose and hold thecoiled segments as they are formed; and a guide shelf on the outside endof each of said slides.

3. Apparatus for forming, from a continuously wound coil of filamentwire, an electric lamp filament having a ceiving the coiled segmentsand, in cooperation with the plurality of coiled segments with afilament-supporting grooves in said slides, to enclose and hold thecoiled segloop between each segment, said apparatus comprising: ments asthey are formed. a jig having a chamber therein; a fixed slide and amovable slide disposed side-by-side in said chamber and in 5 ReferencesCited in h fi of i p t engagement with one another, the engaging facesthereof UNITED STATES PATENTS being provided with cooperatinglongitudinal grooves; 1726 480 Fehse Au g. 27, 1929 and a mandrelshdably seated within said grooves, sald 2,449,653 Isaac Sept 21, 1948mandrel having a plurality of apertures therein for re-

